This and several other laboratories have shown that nonglyosylated and glycosylated proteins assemble into plasma membranes by different pathways. The former may be inserted directly from soluble pools whereas the latter require an internal membranous carrier. The specificities of these processes are unknown. To aid in understanding the process of glycoprotein assembly, we will utilize gas liquid chromatography to determine mannose and fucose in various cell fractions from HeLa cells. The gamma-32P-ATP-enzymatic assay developed by us (Yurchenco and Atkinson, 1975) will be modified for use with GLC to determine mannosyl glycoprotein flows for comparison with fucosyl glycoprotein flows. We have shown that expression of two markedly different classes of cell surface glycopeptides is growth dependent. Rapidly growing cells express a greater proportion of neutral mannose-N-acetylglucosamine containing species. Density inhibited species express a greater proportion of acidic glycopeptides containing sialic acid, galactose, N-acetylglucosamine, mannose and fucose. The mode of control of this expression is unclear along the lines of our previous work coupled with composition data (GLC) and sequence data (use of specific exo- and endoglycosidases).